Three widely accepted goals in the construction industry are:
(1) The development of efficient, economical methods of construction of residential and other buildings;
(2) The development of lightweight but strong structural components for such buildings; and
(3) The development of effective methods of insulating against the passage of heat through the walls of such a building in order to make the heating or cooling of the interior of the building less difficult.
These goals have always been of special importance in the construction of housing for middle and low income groups. The third goal is important for housing in every income group in any climate that is unusually cold or unusually hot, and has become additionally important in recent years in those countries that rely heavily upon imported fuels, as the price of oil and other fuels has risen sharply. The present invention is directed to all three goals.
The use of concrete blocks is one of the most economical forms of building construction. However, although conventional concrete block contains substantial air spaces, it is not very effective in providing the high insulation values that are necessary to conserve high-cost fuels or to provide efficient cooling by air conditioning. Even when the spaces that are ordinarily cast in concrete blocks are filled with insulating material, the multiple paths for heat flow through the remainder of the block tend to reduce the insulating effect materially, and to the extent the spaces in conventional concrete blocks may be filled with steel bars and poured concrete to increase the strength and load-bearing capacity of a wall formed of such blocks, the heat insulating characteristics of the wall are further reduced.
As illustrated by U.S. Pat. No. 338,490 issued in 1886 to Cowan as one example, hollow wall building construction has been known for a very long time. The desirability of providing a good bond between the inner and outer walls of a double wall structure was recognized in the patent literature over 60 years ago, in U.S. Pat. No. 1,312,309 issued in 1919 to Dietrichs.
Since that time many other patents have been issued, in this and in foreign countries, that sought to improve upon known methods of hollow wall construction, but all the structures disclosed in the prior art have a number of serious shortcomings.
One of the most obvious shortcomings in the hollow wall structure disclosed in the Dietrichs patent just referred to, for example, is the fact that the tie rods and spacing blocks there utilized provide only isolated, widely spaced, discontinuous points of support between the inner and outer halves of the hollow wall that is disclosed. This fragmentary, spaced application of stabilizing forces for the inner and outer halves of the hollow wall does not provide adequate support to oppose the bending or bowing forces of compression imposed by the weight of the upper portion of the wall and the rest of the building structure, especially in a multi-story structure. Further, it does not provide sufficient strength to oppose any blows that might be struck against the wall at random locations (as, for example, by a fork lift truck or by the bumper of any other type of vehicle) when the structure in which the wall is incorporated is used for commercial or industrial purposes.
Among additional shortcomings of the Dietrichs invention is the fact that it failed to recognize that if vertical cavities had been included with the individual concrete blocks making up the inner and outer walls, this would have provided spaces for vertical reinforcing elements such as reinforcing steel rods, while still leaving the air spaces for heat insulation between the inner and outer walls themselves. Still another shortcoming in that prior invention is the failure to appreciate the importance of providing positive end-to-end attachment of adjacent building blocks in place of the simple butt joints between the ends of adjacent blocks that are employed in that patent.
French Pat. No. 598,025, issued to Patte et al. in 1925, remedied the first shortcoming in the Dietrichs hollow wall structure, and French Pat. No. 1,071,940 issued to Jamet in 1954 did so partially. However, both of these patents left the other critically important shortcomings of Dietrichs that are mentioned above wholly uncorrected. Another French Pat. No. 907,260 issued to Fluckiger in 1945, partially remedied the first shortcoming in Dietrichs, but did not correct the important third shortcoming.
Another prior art reference that discloses a hollow wall building system is British specification No. 700,325, filed by Hamlin and Guildcrete Limited and published on Nov. 25, 1953. That specification not only failed to correct the second and third above mentioned shortcomings of the Dietrichs hollow wall structure, but actually regressed by returning to the first shortcoming of that earlier structure as well--i.e., scattered, spotty locations of the cross braces between the inner and outer walls.
Since the Dietrichs patent was issued, a tremendous amount of thought and energy has continued to be directed to the development of improved building methods both in this country and abroad. In particular, since World War II increased attention has been given in this country to various improved building methods not only because of the continuing recognition of the acute housing shortage and the great need for middle and low income housing, but also because of the recognition on the part of the housing industry that anyone who succeeded in developing a low-cost but effective form of home construction to help meet these housing needs would be very likely to benefit financially. And for the very same reasons, there have been vigorous and continued efforts in many other countries in the world to develop improved housing construction methods.
Applicant's work has now capped this long period of intensive research with the invention of a hollow building wall that has none of the indicated short-comings of the prior art, and provides a system that is easily and economically produced, is simply and quickly assembled, and results in a strong, well insulated wall that can be incorporated to great advantage in many different types of residences and other buildings.